The sport of sailing rocks because there is such a wide variety of amateur racing available.
Ranging from the Polar Bear winter series that my friends and I do with the local fleet of cruiser racers like this:
Our crew is having lunch as we drift downwind. We are racing, but we are pretty low key about it.
The other end of the spectrum would be one design racing like the Melges 24 worlds that is on right now. There are all amateur crews competing against boats with one or two pro sailors. The racing is at a very high level of competition. The all amateur crews are scored separately and a Corinthian champion is awarded as well.